Three Essays on the Impact of Medicaid Expansion on Cancer Care and Mis-Measured Self-Reports of Cancer Screening Status

Abstract

The dissertation consists of three essays attempting to assess the impact of expanded health insurance policy on cancer care continuum and measure the unbiased program effects after taking care of mis-measured cancer screening self-reports. The first essay examines the impact of the Affordable Care Act’s Medicaid expansion on time to oral cancer treatment initiation since diagnosis, quality of hospital care such as length of stay in the hospital, planned and unplanned readmissions post-surgery, and care outcome such as ninety-day mortality since surgery. The study uses two-way fixed effects linear model analysis under a difference-in-difference estimation setting to show that Medicaid expansion eligibility reduced overall oral cancer treatment initiation timing since diagnosis, including radiation initiation as well as first surgery of the primary site. It also shortened the length of stay in the hospital post-surgery. The second essay assesses the value of electronic medical records from Indiana health information exchange (IHIE) and survey self-reports of Indiana residents seen at Indiana University Health in measuring population-based cancer screening for colorectal, cervical, and breast cancer. Between the two measures of screening, the study examines association using Spearman’s rank correlation and concordance using Percent Agreement and Gwet’s Agreement Coefficient. Health information exchange and self-reports, both provided unique information in measuring cancer screening, and the most robust measurement approach entails collecting screening information from both HIE and patient self-report. In this study, we find evidence of measurement error in self-reports in terms of reporting bias. The majority of the publicly available datasets collect information on cancer screening behavior through patient interviews which are self-reported and may suffer from potential measurement errors. The third essay uses a nationwide population-based database and examines the true, unbiased impact of Medicaid expansion on cancer screening for breast, colorectal, cervical, and prostate cancers after correcting for any bias due to possible misclassification of the self-reported screening status. This study conducts a modified two-way fixed effects probit model under a difference-in-difference estimation setting to identify and correct the errors in the self-reports and estimate the unbiased program effect which shows positive impact on cancer screening with increased effect sizes.